The present invention relates to electrical circuits capable of high-speed operation. More specifically, the present invention relates to semiconductor electrical circuits which are useful both as logic cells and as amplifiers.
In the prior art, semiconductor devices have been classified in two general categories, namely, unipolar devices (usually called field-effect devices) and bipolar devices. Such unipolar and bipolar devices have been used for logic cells and for linear amplifiers in many different circuit configurations.
Logic cells are circuits which operate in two different states and hence are bistable devices. Logic cells have found wide application in the storage of digital information such as used in computers and other data processing equipment. The speed with which bistable devices can be switched from one stable state to the other stable state is important since data processing equipment requires higher and higher speeds of operation.
Also, the density of logic cells, that is the number of logic cells per square area, is another important consideration since data processing equipment requires larger and larger numbers of cells. Also, the closeness of logic cells has a significant impact on the speed at which information can be transferred from cell to cell. The power consumption of logic cells is an additional important factor since excessive heat build-up resulting from high power consumption will destroy the logic cells.
Amplifiers operate over a linear range to amplify by a factor K an input signal, V.sub.in, to produce an output signal, V.sub.out. The magnitude of the amplification factor K is one important characteristic of linear amplifiers. Also, the bandwidth of the amplifier is an important consideration. Also, the maximum voltage, called the voltage breakdown, which the amplifier has is an important consideration for those applications, such as driving a CRT which require high voltage levels.
For input signals which are operating at very high frequencies and over large frequency bandwidths, amplifier circuits have design considerations similar to those of logic cells.